VALD: Multi-Stage Vision Attack Detection for Efficient LVLM Defense

Fuente: arXiv
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Main Authors: Kadvil, Nadav, Fares, Malak, Tal, Ayellet
Format: Preprint
Published: 2026
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author Kadvil, Nadav
Fares, Malak
Tal, Ayellet
author_facet Kadvil, Nadav
Fares, Malak
Tal, Ayellet
contents Large Vision-Language Models (LVLMs) can be vulnerable to adversarial images that subtly bias their outputs toward plausible yet incorrect responses. We introduce a general, efficient, and training-free defense that combines image transformations with agentic data consolidation to recover correct model behavior. A key component of our approach is a two-stage detection mechanism that quickly filters out the majority of clean inputs. We first assess image consistency under content-preserving transformations at negligible computational cost. For more challenging cases, we examine discrepancies in a text-embedding space. Only when necessary do we invoke a powerful LLM to resolve attack-induced divergences. A key idea is to consolidate multiple responses, leveraging both their similarities and their differences. We show that our method achieves state-of-the-art accuracy while maintaining notable efficiency: most clean images skip costly processing, and even in the presence of numerous adversarial examples, the overhead remains minimal.
format Preprint
id arxiv_https___arxiv_org_abs_2602_19570
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle VALD: Multi-Stage Vision Attack Detection for Efficient LVLM Defense
Kadvil, Nadav
Fares, Malak
Tal, Ayellet
Computer Vision and Pattern Recognition
Large Vision-Language Models (LVLMs) can be vulnerable to adversarial images that subtly bias their outputs toward plausible yet incorrect responses. We introduce a general, efficient, and training-free defense that combines image transformations with agentic data consolidation to recover correct model behavior. A key component of our approach is a two-stage detection mechanism that quickly filters out the majority of clean inputs. We first assess image consistency under content-preserving transformations at negligible computational cost. For more challenging cases, we examine discrepancies in a text-embedding space. Only when necessary do we invoke a powerful LLM to resolve attack-induced divergences. A key idea is to consolidate multiple responses, leveraging both their similarities and their differences. We show that our method achieves state-of-the-art accuracy while maintaining notable efficiency: most clean images skip costly processing, and even in the presence of numerous adversarial examples, the overhead remains minimal.
title VALD: Multi-Stage Vision Attack Detection for Efficient LVLM Defense
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2602.19570